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Electronics DIY LVDS controller - all soldered, no video?

Discussion in 'Modding' started by PsychoI3oy, 23 May 2004.

  1. PsychoI3oy

    PsychoI3oy Minimodder

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    Ok, the iron-the-toner-on-the-board method worked, it just took a few tries. The first try I had the iron on the hottest setting and pushed hard and ended up mushing the toner all over the place. The second try i didn't push so hard and hardly got any toner in the small traces. Third try was the charm:

    [​IMG]

    obviously sketchy in the bigger areas but no problem, the small traces were perfect. I filled in areas with a sharpie and scraped off some to keep the ccfl ground seperate from common ground because i'm still not sure how i'm going to power the (14-18v) ccfl. I also wrote "Widgetron LVDS v.1.0" and noted the ccfl ground and common ground.

    [​IMG]

    then i drilled the holes with a 1/16" drillbit. I would have liked smaller but didn't have any. i re-masked the areas around the holes to make sure the etchant didn't get in the edges and provide big enough pads to solder to. I then cut the board off the biger piece.

    [​IMG]

    then into the etchant bath for about 10-15 minutes, keeping a close eye on it. the instructions say 20 minutes but that's for whole boards, this is tiny and I didn't want to over-etch my smaller traces. The handwriting on the top and side didn't get masked enough but oh well, i know what's what.

    [​IMG]

    cleaned up with the kit's masking remover (rubbing alcohol from the smell of it) and voila.

    [​IMG]

    then test fit the components on and they fit perfectly

    [​IMG]


    so now comes the hard part of soldering the FREAKING SMALL chip onto the board without any solder bridges. anyone got any points on doing this?
     
    Last edited: 6 Jun 2004
  2. nleahcim

    nleahcim What's a Dremel?

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    First of all, nice etching! :thumb: Very good for a first try. Second of all whenever a toner transfer isn't 100% perfect for me I use a fine tipped sharpie to clean it up - it ends up looking better. (oh and the pen doubles as a great way to label CD-Rs!)

    But anyways as to your question - on the ic try to solder 1 pin on one corner, then the pin on the opposite corner from that. This is just to make sure it is lined up properly. Then either you can go and solder each pin individually (starting from one of the unsoldered corners) or you can do what I like to do - and just pool a whole bunch of solder along an entire side - then pull off the excess with solder wick. Same technique for the connector. Good luck!
     
  3. SteveyG

    SteveyG Electromodder

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    It doesn't look like you cleaned your PCB before processing, so you ended up with slightly duff results. Remember to use wire wool/polifix block before any kind of processing on bare copper clad board. It will give you much sharper PCB's (and stuff you write on with pen will come out better).

    You can solder surface mount devices very rapidly with a 0.1mm bit and some fine solder. The trick is to use the smallest amount of solder you can get away with.
     
  4. PsychoI3oy

    PsychoI3oy Minimodder

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    well the pcb was cleaned with rubbing alcohol and the scrubby pad that came with the kit, i'm not too worried about the results, the important traces are all intact.

    and i didn't see your reply before soldering but that's basically what I did. I previously threw my soldering tip in the chuck of my drill and sharpened it with a file, so it was fine enough. I started by tinning the whole board, then cleaning up excess (lots) with desoldering braid, leaving me with a nice, flat, evenly tinned set of traces. I taped the board to my desk with duct tape, then positioned my chip on it and used a very thin strip of duct tape to hold it in place. i soldered by just touching the tip of the pin and the trace, which melted the tinning on the board and the solder left on the trace after i had desoldered it from the laptop motherboard. here's the results:

    [​IMG]
    note that anything that looks like solder bridges is either just bad jpeg compression, a camera perspective problem, or actual lumpy solder i fixed after taking the picture.

    after a big sigh and an un-cricking of my neck i proceded to solder on the 50 pin connector for the lcd, then wired up my VESA connector and lines for power and ground.


    [​IMG]

    the mess of wires from the back:
    [​IMG]

    everything:
    [​IMG]

    the grey ribbon cable was a parallel port that was supposed to connect to a header of an old motherboard, it's only 25 pins but the 26th pin on vesa is not connected so i didn't worry about it. the black cables are ground, one for the chip and lcd, one for the ccfl, again because i'm probably going to be sending -5v to the ground for the ccfl to be able to get 17v total. the orange wires are 3.3v for the chip and 3.3v for the lcd, which i'll shark off the ATX cable.

    my neck is very sore, but i'm mostly done with it, now comes the hardest part of connecting and tweaking. i'll be powering down the celeron box that this is for tomorrow, scalping 3.3v, -5v, and 12v from ATX, and seeing if i can get the ccfl to power up, if not i may have to connect one of the other pins for the ccfl to ground through a 7k ohm resistor, as i think it's contrast control for the screen. I also burnt out my multimeter trying to test the mA output of one of my drill batteries, hopefully it's just the fuse.

    that's all for now, hopefully i can post tomorrow with a nice picture of my 13.3" tft in wonderful shining glory showing the linux console of my celeron box.
     
  5. PsychoI3oy

    PsychoI3oy Minimodder

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    or i could RIP THE FREAKING CONNECTOR RIGHT OFF THE CIRCUIT BOARD

    i was pushing the ribbon cable onto the connector for about the 3rd time and it got away from me and i ended up pushing on it sideways. hard.

    there's a half dozen pins still soldered to the board, the rest came up with the connector. ARGH

    i dunno if i want to do this anymore, this is pissing me right the heck off.

    oh, and i can't get the backlight inverter powered. dunno why it's not working but it ain't. but the lcd powers fine on 3.3v from my ATX supply, and i had just finished soldering the power wires into the ATX supply and was going to test it when i snapped the connector. i'm not even looking at it right now. it's pissing me off too much.
     
  6. ConKbot of Doom

    ConKbot of Doom Minimodder

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    I know how you feel, especially the sore neck, on the project I'm doing, I have everything the way I think it should be, but it isn't working, really making me mad, and I have a nice and sore neck too, I need to get a table about 4ft tall to do my soldering work on. After I was done soldering, my neck muscles tightened, and I couldnt look down. I had to tilt my head to the right and glance off to the side to see down.

    Good luck man
     
  7. PsychoI3oy

    PsychoI3oy Minimodder

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    thanks for the sympathy, glad to know i'm not the only one working in inadequate work conditions

    so, do i put the connector back together and resolder it and keep going or give this one up? how much of a chance does it have of working anyway?
     
  8. PsychoI3oy

    PsychoI3oy Minimodder

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  9. woodshop

    woodshop UnSeenly

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    put it back togeather i wana know if this will work (i have no clue if it will.) although it does seam pretty lacking
     
  10. PsychoI3oy

    PsychoI3oy Minimodder

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    i wanna know if it'll work, too. darn it. well it'll be tomorrow before i can try piecing things back together, i don't have enough light in here right now.


    why do you say it seems pretty lacking?
     
  11. alianyn

    alianyn What's a Dremel?

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    don`t be discouraged by this, only a chance to imporve.
    stuff like that happens all the time. especially if you delve as deep as that into the "black art" :thumb:

    having said that, i feel for you, just the other day i burned my lip on an opamp i inserted in reverse in an audio amplifier i`m designing for a friend.
    don`t ask how!

    so you see you only broke the part, no scars on you - keep it up. i`d love to see you make this work!
     
  12. TheAnimus

    TheAnimus Banned

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    its no fun if its not a challenge, u don't end up learning anything.

    you've come this far might as well go the extra few miles, but mabye stick it on the shelf for a week or 2, until your hatred for the PCB dies down a bit.
     
  13. davew

    davew What's a Dremel?

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    Gwan tell us :hehe: Were you testing how hot it is? I usually cant tell if it's getting hot using my fingers unless it's really burning them.

    As for giving up on getting the display to work, DONT! :D Surely all the work done so far is worth finishing off. And we'd all like to see it working at the end :)
     
  14. PsychoI3oy

    PsychoI3oy Minimodder

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    alrighty, thanks for the support guys.

    i'll try to resurrect this thing this afternoon and get the plug back on and pick up where i left off (basically just plugging it into the video card then going from there testing what other wires need to be hooked up). guess an lcd without a backlight is ok, but it's not gonna look great.
     
  15. sk8ero

    sk8ero What's a Dremel?

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    ouch, this stuff happens to me all the time, i painted my case, take it inside wen it dries, and soemthing falls on it ****ing up my nice new paint job which i put hours of wet and drying and painting into GRRRR but just try again its all worth it
     
  16. PsychoI3oy

    PsychoI3oy Minimodder

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    thanks for all the support guys, i managed to piece the connector back together and i'm back where i was yesterday morning, with lcd powering but no video

    now, here may be a fundamental flaw with my initial wiring, how are the pins on the VFC counted? according to this: http://www.hardwarebook.net/connector/av/vesafeature.html they're 2 4 6 8 ... across the top row. but according to this: http://www.epanorama.net/documents/pc/vga_feature.html it's 1 2 3 4 5 6 ... across the top row.

    i also know that i need to tie all 3 'select internal' lines to +5v (According to the second link there) to activate the internal video, which shouldn't be a problem. the other input i'm trying to figure out is the 'enable' pin on the LVDS chip, wether it wants ground, 3.3v, or something else.

    anyone have any clarifications on the VESA pinout?
     
  17. star882

    star882 What's a Dremel?

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    The correct pinout is at http://inf33-www.informatik.unibw-muenchen.de/infothek/computer/tutorial/eprmhtml/eprm/268.htm .
     
  18. Lynx

    Lynx What's a Dremel?

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    By teh Enable pin I assume you mean Shutdown(bar) on pin 28. The Bar accross the top indicates that 5v is low. So to enable the chip you need to connect pin 28 to VCC
     
  19. PsychoI3oy

    PsychoI3oy Minimodder

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    no, i mean D20 which is listed as enable. looking at page 8 of the datasheet, when they did the test pattern it looked like D20 (as well as 18 & 19) were pulled high, so i'm assuming i just tie it to 3.3v and it'll work. the SHUTDN pin only needs to be used to kill the chip (i.e. go into sleep/battery saving mode) and from what i remember(not having the datasheet in front of me) it gets tied to ground for shutdown, and unconnected for normal operation.

    but first i have to reconnect all the wires so the VESA inputs are all correct. shazbot.
     
  20. PsychoI3oy

    PsychoI3oy Minimodder

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    yeah, i saw that, but how are the pins numbered? i'm assuming 2 4 6 8... across the top row and 1 3 5 7... across the bottom row. looks like my source used one pin numbering scheme but a pinout list that used another (1 2 3 4... across the top) numbering scheme.

    edit: btw, there are 3 lists of pinouts on that page, but i'm assuming you're referring to the top one which is congruent to other VESA Feature Connector pinouts i've seen (after the fact, of course). Hopefully i haven't fried anything in the chip or on the video card, but then again i haven't 'enable'd the chip or the VFC so i think i'm ok.
     

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